SWB TBE: Fix constant in create_random_vector() to allow more reliable fixed point port.

The constant "0.0078f" should read 0.0078125f, which is 1/128.

void create_random_vector(
    float output[],       /* o  : output random vector      */
    const int16_t length, /* i  : length of random vector   */
    int16_t seed[]        /* i/o: start seed                */
)
{
    int16_t i, j, k;
    float scale1, scale2;

    j = (int16_t) ( own_random( &seed[0] ) * 0.0078f );
    j = abs( j ) & 0xff;

should be refactored to

    j = (int16_t) ( own_random( &seed[0] ) * 0.0078125f );
    j = min(abs(j), 255);

This allows a more reliable and bit exact output for the fixed point port, simply a division by 128 or right shift by 7